This section is intended to introduce the reader to various aspects of art, which may be related to various aspects of the present technique that are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
Fans and heat sinks are often mounted in electronic devices to cool the various internal components. For example, computers often have a heat sink and fan mounted to the processor. Unfortunately, these heat sinks only accommodate a single fan above the processor. In addition, fans are often mounted within the computer housing, such as along the walls or within ductwork. The wall mounted fans circulate air through the computer housing, yet airflows are not directed onto specific components. Thus, wall mounted fans are not particularly efficient at cooling specific components. The duct mounted fans are more efficient at cooling specific components, because the ducts direct the airflows onto the components. However, space limitations often preclude the use of ducts.
In computers, such as rack mount servers, fans are typically axial fans having a relatively small diameter, which limits their airflow potential. To compensate for this small diameter, axial fans are operated at a high rotational speed, e.g., 15,000 RPM, to develop the desired airflow. Unfortunately, this high rotational speed creates significant noise. In certain applications, these axial fans may include counter rotating impellers to increase the airflow. As a result, the counter rotating impellers double the number of motors, the power requirement, and the noise output of the axial fan. In servers and other applications, redundancies are desirable to ensure continuous airflow in the event that one of the fans malfunctions or fails to operate. A typical server often has between ten and twenty axial fans and, thus, a rack system can have over one hundred axial fans. Thus, the noise and power requirements of these fans can be quite significant.